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- //
- // csc wsserver.cs
- // wsserver.exe
- using System;
- using System.Net;
- using System.Net.Sockets;
- using System.Text;
- using System.Text.RegularExpressions;
- class Server {
- public static void Main() {
- string ip = "127.0.0.1";
- int port = 80;
- var server = new TcpListener(IPAddress.Parse(ip), port);
- server.Start();
- Console.WriteLine("Server has started on {0}:{1}, Waiting for a connection...", ip, port);
- TcpClient client = server.AcceptTcpClient();
- Console.WriteLine("A client connected.");
- NetworkStream stream = client.GetStream();
- // enter to an infinite cycle to be able to handle every change in stream
- while (true) {
- while (!stream.DataAvailable);
- while (client.Available < 3); // match against "get"
- byte[] bytes = new byte[client.Available];
- stream.Read(bytes, 0, client.Available);
- string s = Encoding.UTF8.GetString(bytes);
- if (Regex.IsMatch(s, "^GET", RegexOptions.IgnoreCase)) {
- Console.WriteLine("=====Handshaking from client=====\n{0}", s);
- // 1. Obtain the value of the "Sec-WebSocket-Key" request header without any leading or trailing whitespace
- // 2. Concatenate it with "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" (a special GUID specified by RFC 6455)
- // 3. Compute SHA-1 and Base64 hash of the new value
- // 4. Write the hash back as the value of "Sec-WebSocket-Accept" response header in an HTTP response
- string swk = Regex.Match(s, "Sec-WebSocket-Key: (.*)").Groups[1].Value.Trim();
- string swka = swk + "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
- byte[] swkaSha1 = System.Security.Cryptography.SHA1.Create().ComputeHash(Encoding.UTF8.GetBytes(swka));
- string swkaSha1Base64 = Convert.ToBase64String(swkaSha1);
- // HTTP/1.1 defines the sequence CR LF as the end-of-line marker
- byte[] response = Encoding.UTF8.GetBytes(
- "HTTP/1.1 101 Switching Protocols\r\n" +
- "Connection: Upgrade\r\n" +
- "Upgrade: websocket\r\n" +
- "Sec-WebSocket-Accept: " + swkaSha1Base64 + "\r\n\r\n");
- stream.Write(response, 0, response.Length);
- } else {
- bool fin = (bytes[0] & 0b10000000) != 0,
- mask = (bytes[1] & 0b10000000) != 0; // must be true, "All messages from the client to the server have this bit set"
- int opcode = bytes[0] & 0b00001111, // expecting 1 - text message
- msglen = bytes[1] - 128, // & 0111 1111
- offset = 2;
- if (msglen == 126) {
- // was ToUInt16(bytes, offset) but the result is incorrect
- msglen = BitConverter.ToUInt16(new byte[] { bytes[3], bytes[2] }, 0);
- offset = 4;
- } else if (msglen == 127) {
- Console.WriteLine("TODO: msglen == 127, needs qword to store msglen");
- // i don't really know the byte order, please edit this
- // msglen = BitConverter.ToUInt64(new byte[] { bytes[5], bytes[4], bytes[3], bytes[2], bytes[9], bytes[8], bytes[7], bytes[6] }, 0);
- // offset = 10;
- }
- if (msglen == 0)
- Console.WriteLine("msglen == 0");
- else if (mask) {
- byte[] decoded = new byte[msglen];
- byte[] masks = new byte[4] { bytes[offset], bytes[offset + 1], bytes[offset + 2], bytes[offset + 3] };
- offset += 4;
- for (int i = 0; i < msglen; ++i)
- decoded[i] = (byte)(bytes[offset + i] ^ masks[i % 4]);
- string text = Encoding.UTF8.GetString(decoded);
- Console.WriteLine("{0}", text);
- } else
- Console.WriteLine("mask bit not set");
- Console.WriteLine();
- }
- }
- }
- }
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